Insulin deficiency and cell proliferation in oral mucosal epithelium of the rat.

The duration of the cell cycle (C) and its component phases (G1, S, G2 and M), the rate of cell proliferation, and the renewal time, in the epithelium of the hard palate of alloxan-diabetic rats have been determined and compared with values of the same variables obtained previously from normal rats. The data have been derived by means of autoradiography with [3H]thymidine and the method of labelled mitoses. The values for the normal animals were found to be: G1 = 38 hours, S = 8 hours, G2 = 1 hour, M = 1 hour, C = 48 hours (or 2.1%/hour); and for the diabetic animals were: G1 = 42.5 hours, S = 8.5 hours, G2 = 1 hour, M = 1 hour, C = 53 hours (or 1.9%/hour); and for the renewal time for the epithelium, 6.5-8 days. In the diabetic animals the duration of S was increased by 6%, G1 by 12% and the cell cycle by about 10%. The reduced rate of cell proliferation that is associated with insulin deficiency may contribute to the slower rate of wound healing in subjects with diabetes mellitus.